digraph G {
  conj[label="∧", shape=rectangle];
  disj[label="∨", shape=rectangle];
  p1[label=<p<sub>1</sub>>, shape=circle];
  p2[label=<p<sub>2</sub>>, shape=circle];
  p3[label=<p<sub>3</sub>>, shape=circle];
  {rank=same; p1, disj}
  {rank=same; p2, p3}
  conj -> disj;
  conj -> p1;
  disj -> p2;
  disj -> p3;
  }
